In post-combustion CO2 capture, waste biomass is a favourable precursor to prepare porous carbons due to its low cost, renewability, and unique microstructures. This study presents a facile method for preparing N-doping porous carbons. Palm kernel shell was selected as carbon precursor, and its inherent silica species acted as a natural template to form hierarchical pores. The obtained samples exhibit predominant characteristics with highly developed micropores and a high N content providing an important contribution to CO2 adsorption capacity, which can reach up to 5.29 and 2.30 mmol/g under 100 kPa at 25 and 60 degrees C, respectively. Moreover, the resultant porous carbons also exhibit excellent cycling stability after 20 cycles. Furthermore, the activation mechanism was investigated by the quantitative thermogravimetry-mass spectrometry (TG-MS) method.